2D Piezoelectric Bi2 MoO6 Nanoribbons for GSH-Enhanced Sonodynamic Therapy

Anion exchange regulated charge separation engineering in bismuth nanoflowers for sonocatalytic radio-immunotherapy

Ultrasound and X-ray are considered potential options in cancer therapy due to their superior tissue penetration capabilities. Developing effective radiosensitizers is crucial for advancing cancer treatment as they enhance the effectiveness of radiation and sonodynamic therapies while minimizing their side effects. This study aimed to design a degradable bismuth-based heterojunction BiF3-Bi2O3-x:Sx-PEG (BFOSP) radiosensitizer using anion-exchange-regulated charge separation engineering. The heterojunction regulated the bandgap, improved charge carrier mobility, and enhanced reactive oxygen species generation efficiency by introducing O and S anions, enhancing the synergistic effects of sonodynamic therapy and radiotherapy. Sonodynamic therapy reduces the required radiotherapy dose, thus improving the synergistic therapeutic efficacy while enhancing treatment safety. The degradation and oxidative stress effects of BFOSP further disrupted redox balance in the tumor microenvironment while inducing tumor cell apoptosis, ferroptosis, and immunogenic cell death, activating systemic immune responses. This study introduces a reasonable design strategy for degradable radiosensitizers, offering a promising approach to improving synergy and advancing comprehensive cancer therapy.

Switchable Nanophotosensitizers as Pyroptosis Inducers for Targeted Boosting of Antitumor Photoimmunotherapy

Photodynamic therapy (PDT) has emerged as a promising modality for cancer treatment, but its clinical application is constrained by unexpected phototoxicity arising from nonspecific photosensitizer activation and their "always-on" nature. Herein, we developed a switchable nanophotosensitizer, poly(cation-π) nanoparticles (NP), which achieves supramolecular assembly through cation-π interactions. By coupling choline cationic moieties with aromatic photosensitizers (ZnPc), the polymer facilitates self-assembly driven by cation-π interactions for NP engineering. Surprisingly, the photoactivity of ZnPc was completely quenched upon complexation via cation-π interactions, thereby significantly avoiding skin phototoxicity. Upon targeting tumor cells, NP undergoes a GSH-responsive degradation process that weakens cation-π interactions, leading to spontaneous restoration of photoactivity and amplifying tumor immunogenic pyroptosis. In vivo studies demonstrated that NP achieved a high tumor inhibition rate of 84% while effectively avoiding skin phototoxicity. This work provides a novel perspective for enhancing the safety and efficacy of PDT-based tumor treatment.

Sonosensitizers for Sonodynamic Therapy: Current Progress and Future Perspectives

Sonodynamic therapy (SDT) is a novel non-invasive treatment method that combines low-intensity ultrasound and sonosensitizers. Compared with photodynamic therapy, SDT has the advantages of deeper tissue penetration, higher accuracy and fewer adverse reactions. Sonosensitizers are essential for the efficacy of SDT. Sonosensitizers have the advantages of clear structure, easy monitoring, evaluation of drug metabolism and clinical transformation, etc. Notably, biochemical techniques can be used in the field of sonosensitizers and SDT to overcome inherent barriers and achieve sustainable innovation. This article first summarizes the molecular mechanism of SDT, focusing on organic sonosensitizers, inorganic nano-sonosensitizers and multi-functional drug delivery systems with targeting, penetration and imaging functions after a series of modifications. This review provides ideas and references for the design of sonosensitizers and SDT and promotes their future transformation into clinical applications.

Dopant-Regulated Piezocatalysts Evoke Sonopiezoelectric and Enzymatic PANoptosis for Synergistic Cancer Therapy

Piezocatalyst-enabled sonopiezoelectric therapy offers noninvasive treatment with high spatiotemporal selectivity, yet existing piezocatalysts are limited by suboptimal efficacy, cancer cell resistance to oxidative stress, and biosafety concerns. Here, hafnia (HfO2), one of the only few FDA-approved inorganic nanomaterials for clinical trials, is identified as a promising piezocatalyst with high translational potential for sonopiezoelectric and enzymatic PANoptosis-boosted nanocatalytic therapy. Specifically, engineered transition metal-substituted HfO2 nanocatalysts are synthesized to optimize piezoelectric and enzyme-mimicking activities. Among these, Mn-substituted HfO2 with a 20% Mn ratio (HMO) demonstrates superior performance in sono-triggered reactive oxygen species generation, attributed to its reduced bandgap and increased oxygen vacancies. HMO also exhibits multiple enzyme-mimicking activities, including peroxidase (POD), catalase (CAT), and glutathione peroxidase (GPx), amplifying oxidative stress through tumor-specific catalytic reactions. These dual catalytic effects enable the activation of cancer cell PANoptosis to elicit a robust antitumor immune response. Biological evaluations show significant tumor suppression and antitumor immune responses by HMO-mediated nanocatalytic therapy. Unlike utilizing the radiosensitization ability of HfO2 in the clinic, this work unveils the distinctive sonopiezoelectric effect and multienzymatic activities of HfO2-based nanocatalysts for biomedical applications, holding the potential to overcome the challenges of radiation damage associated with radiotherapy.

NIR-II imaging guided on-site size variable clustered nanosystem to potentiate sonodynamic therapy in deep-seated tumors

The insufficient enrichment and penetration of sonosensitizers in the tumor site hamper the antitumor efficiency of sonodynamic therapy (SDT). Herein, tumor-acidity and photothermal controlled nanosystems (NTTD), which coloaded a new type of sonosensitizers, Na3TiF6 NPs and second near-infrared (NIR-II) emissive AIEgen (T1), have been developed to achieve highly efficient SDT/photothermal therapy (PTT) in deep-seated tumors. On one hand, NTTD includes ultrasmall Na3TiF6 NPs with increased oxygen vacancies, narrow bandgap (2.82 eV) and preferrable absorption capability of H2O and O2 molecules, guaranteeing powerful generation of reactive oxygen species (ROS) under US stimulation. On the other hand, with the assistance of the acidic/photothermal responses and deep penetrated NIR-II fluorescence imaging (up to 7 mm), NTTD undergo in situ "two-step" size transformation to achieve enhanced retention and penetration of sonosensitizers in tumor area with high spatiotemporal controllability. In 4T1 tumor model, compared to passive targeting participated NTT group, NTTD elongated the tumor retention time to 60 h and revealed enhanced imaging signal (∼2.4 fold). Further photoirradiation of NTTD assisted ∼4.5-fold enhancement of penetration ability. SDT/PTT synergies have evoked significant ROS generation and tumor inhibition rate of 75.2 % in vivo. This study presents an innovative strategy to exploit novel nano-sonosensitizers with precisely improved tumor accumulation and penetration.

Ruthenium Single-Atom Nanozyme Driven Sonosensitizer with Oxygen Vacancies Enhances Electron-Hole Separation Efficacy and Remodels Tumor Microenvironment for Sonodynamic-Amplified Ferroptosis

Sonodynamic therapy (SDT) has emerged as a promising noninvasive approach for tumor therapy. However, the effectiveness of traditional inorganic semiconductor sonosensitizers is hindered by rapid electron (e-) and hole (h+) recombination under ultrasonic (US) stimulation, as well as the hypoxic and reductive conditions of tumor microenvironment (TME), which limit the generation of reactive oxygen species (ROS). Herein, a ruthenium (Ru) single-atom nanozyme-driven superimposition-enhanced titanium dioxide-based sonosensitizer (Ru/TiO2-x SAE) is presented that features sufficient oxygen vacancies and high e-/h+ separation efficiency. Through synchrotron radiation-based X-ray absorption spectroscopy and extended X-ray absorption fine structure analysis it is confirmed that oxygen vacancies in TiO2-x nanoparticles promote the immobilization of single-atomic Ru, forming Ru-O₄ active sites. Density functional theory calculations demonstrate that oxygen vacancies alter the electronic structure of nanosensitizer, enhanced e-/h+ separation, increasing oxygen adsorption, and accelerating reaction kinetics under US stimulation, ultimately improving ROS production. Moreover, Ru/TiO2-x SAE boosts sonodynamic efficacy by mitigating the hypoxic and reductive TME. This is attributed to its catalase- and glutathione peroxidase 4-like activities, which facilitate the generation of ROS and trigger lipid peroxidation-mediated ferroptosis. These findings highlight the innovative role of single-atom Ru in optimizing sonosensitizers for SDT-induced ferroptosis, demonstrating its potential for advancing cancer therapy.

Hydrogel Containing Bismuth Molybdate Nanosheets with Piezoelectricity and Nanoenzyme Activity for Promoting Osteoblast Responses

The development of piezoelectric biomaterials with the capability to produce electrical signals and scavenge reactive oxygen species (ROS) is a novel strategy for stimulating osteoblast responses and promoting bone regeneration. Herein, tungsten (W), iridium (Ir), and ruthenium (Ru) codoped bismuth molybdate (4(W/Ru/Ir)-BMO) nanosheets with improved piezoelectricity and enzyme-like (CAT-like and SOD-like) activities were constructed by using the hydrothermal method. A composite hydrogel of oxidized sodium alginate/gelatin (OSA/GEL) and 4(W/Ru/Ir)-BMO (OSA/GEL/4-B) was also prepared. Due to the presence of 4(W/Ru/Ir)-BMO, OSA/GEL/4-B exhibited not only piezoelectricity but also enzyme-like activities. Under ultrasound (US), OSA/GEL/4-B generated electrical signals that significantly promoted the proliferation and osteogenic differentiation of bone marrow stromal cells. Furthermore, the piezoelectric effect of OSA/GEL/4-B improved the CAT-like (production of oxygen) and SOD-like (scavenger of ROS) activities. The improved piezoelectricity of 4(W/Ru/Ir)-BMO was attributed to the codoping of W, Ir, and Ru ions, which resulted in lattice distortion and enhanced crystal asymmetry, which produced electrical signals for regulating the osteogenic microenvironment. Moreover, the improvement of enzyme-like activities was attributed to the enhanced piezoelectric effect by the codoping of W, Ir, and Ru ions, which generated a piezoelectric field triggered by US that accelerated electron transfer for alleviating cellular oxidative stress and provided an antioxidant microenvironment for osteoblast responses. This piezoelectric hydrogel may provide a novel pathway for promoting osteogenic differentiation and bone regeneration.

Novel hollow ultrasound-triggered ZnFe2O4-Bi2MoO6 S-scheme heterojunction for efficient ferroptosis-based tumor therapy

This study addresses the challenge of enhancing ferroptosis efficacy for tumor therapy, particularly the limited therapeutic efficiency of current inducers due to tumor microenvironment constraints. Herein, we developed a hollow ultrasound-triggered ZnFe2O4-Bi2MoO6 (ZB) S-scheme heterojunction loaded with artesunate (ART) to overcome these limitations. The ZB heterojunction with a particle size of ∼250 nm efficiently separates electron-hole pairs under ultrasound (US), promoting the generation of reactive oxygen species (ROS). The photodynamic effect of ZB further boosts ROS production, while ART, controlled-released by phase change materials under laser/US stimulation, enhances ROS production via Fe2+-mediated decomposition. This triple-enhanced strategy accumulates lipid peroxidation (LPO), significantly improving ferroptosis effects with a tumor suppression rate of 94.3 %. Moreover, ZB enables multimodal imaging and stimulates antitumor immunity, demonstrating its potential as a diagnostic and therapeutic agent. Our findings demonstrate the potential of this ZB@ART system in advancing ferroptosis-based tumor therapies, inspiring future designs of efficient ferroptosis inducers.

Bimetallic peroxide-based nanotherapeutics for immunometabolic intervention and induction of immunogenic cell death to augment cancer immunotherapy

Immunotherapy has transformed cancer treatment, but its efficacy is often limited by the immunosuppressive characteristics of the tumor microenvironment (TME), which are predominantly influenced by the metabolism of cancer cells. Among these metabolic pathways, the indoleamine 2,3-dioxygenase (IDO) pathway is particularly crucial, as it significantly contributes to TME suppression and influences immune cell activity. Additionally, inducing immunogenic cell death (ICD) in tumor cells can reverse the immunosuppressive TME, thereby enhancing the efficacy of immunotherapy. Herein, we develop CGDMRR, a novel bimetallic peroxide-based nanodrug based on copper-cerium peroxide nanoparticles. These nanotherapeutics are engineered to mitigate tumor hypoxia and deliver therapeutics such as 1-methyltryptophan (1MT), glucose oxidase (GOx), and doxorubicin (Dox) in a targeted manner. The design aims to alleviate tumor hypoxia, reduce the immunosuppressive effects of the IDO pathway, and promote ICD. CGDMRR effectively inhibits the growth of 4T1 tumors and elicits antitumor immune responses by leveraging immunometabolic interventions and therapies that induce ICD. Furthermore, when CGDMRR is combined with a clinically certified anti-PD-L1 antibody, its efficacy in inhibiting tumor growth is enhanced. This improved efficacy extends beyond unilateral tumor models, also affecting bilateral tumors and lung metastases, due to the activation of systemic antitumor immunity. This study underscores CGDMRR's potential to augment the efficacy of PD-L1 blockade in breast cancer immunotherapy.

Targeted bismuth-based materials for cancer

The use of bismuth and its compounds in biomedicine has developed rapidly in recent years. Due to their unique properties, there are great opportunities for the development of new non-invasive strategies for the early diagnosis and effective treatment of cancers. This perspective highlights key fabrication methods to generate well-defined and clinically relevant bismuth materials of varying characteristics. On the one hand, this opens up a wide range of possibilities for unimodal and multimodal imaging. On the other hand, effective treatment strategies, which are increasingly based on combinatorial therapies, are given a great deal of attention. One of the biggest challenges remains the selective tumour targeting, whether active or passive. Here we present an overview on new developments of bismuth based materials moving forward from a simple enrichment at the tumour site via uptake by the mononuclear phagocytic system (MPS) to a more active tumour specific targeting via covalent modification with tumour-seeking molecules based on either small or antibody-derived molecules.

Advances in Sonodynamic Therapy: Focus on Ferroptosis

Ferroptosis is a nonapoptotic form of cell death discovered in 2012. Noninvasive treatments regulating ferroptosis are important for a wide range of diseases. Among the noninvasive treatments, sonodynamic therapy (SDT) has become promising due to its strong tissue penetration and few side effects. In recent years, targeted drug delivery platforms constructed on the basis of SDT have provided an efficient delivery mode for the regulation of ferroptosis. Based on the latest research reports, this Perspective introduces the basic mechanism of SDT and the influencing factors of therapeutic effects, elucidates the significance of ferroptosis-targeted SDT, and summarizes the recent studies on ferroptosis-targeted SDT through different pathways. We also present innovative studies of composite ultrasound-responsive drug delivery platforms. Finally, a brief summary and outlook based on current ferroptosis-targeted SDT are presented.

Preparation of La2(WO4)3/CuWO4 composite nanomaterials with enhanced sonodynamic anti-glioma activity

Introduction

Sonodynamic therapy (SDT) is an innovative way to treat tumors by activating sonosensitizers via ultrasound (US). The development of sonosensitizers with high sonodynamic activity is the key to promote the clinical application of SDT.

Methods

In this study, a novel sonosensitizer, La2(WO4)3/CuWO4 composite LC-10, was prepared by two-step hydrothermal method and characterized. In addition, the sonodynamic antitumor activity of La2(WO4)3/CuWO4 composite LC-10 was investigated using u251 glioma cells as a model.

Results and Discussion

The results showed that compared with La2(WO4)3 and CuWO4, La2(WO4)3/CuWO4 composite had better sonodynamic antitumor activity, and LC-10 had good biosafety at concentrations below 50 μg/mL. After La2(WO4)3 and CuWO4 formed La2(WO4)3/CuWO4 composite, the recombination of electron-hole (e --h +) pairs were effectively inhibited, and more strongly oxidizing ROS was produced, inducing apoptosis of u251 glioma cells. In which, singlet oxygen (1O2) and hydroxyl radical (·OH), especially the production of ⋅OH, played an important role in the La2(WO4)3/CuWO4 composite mediated SDT antitumor process. The results of this study would offer a foundation for the design of CuWO4 base nano-sonosensitizers and its further clinical application in SDT antitumor. In addition, it also provided a new strategy for the design and development of novel nano-sonosensitizers with excellent sonodynamic activity.

Progress and Perspectives in 2D Piezoelectric Materials for Piezotronics and Piezo-Phototronics

The emergence of two-dimensional (2D) materials has catalyzed significant advancements in the fields of piezotronics and piezo-phototronics, owing to their exceptional mechanical, electronic, and optical properties. This review provides a comprehensive examination of key 2D piezoelectric and piezo-phototronic materials, including transition metal dichalcogenides, hexagonal boron nitride (h-BN), and phosphorene, with an emphasis on their unique advantages and recent research progress. The underlying principles of piezotronics and piezo-phototronics in 2D materials is discussed, focusing on the fundamental mechanisms which enable these phenomena. Additionally, it is analyzed factors affecting piezoelectric and piezo-photoelectric properties, with a particular focus on the intrinsic piezoelectricity of 2D materials and the enhancement of out-of-plane polarization through various modulation techniques and materials engineering approaches. The potential applications of these materials are explored from piezoelectric nanogenerators to piezo-phototronic devices and healthcare. This review addresses future challenges and opportunities, highlighting the transformative impact of 2D materials on the development of next-generation electronic, optoelectronic, and biomedical devices.

Quasi Fe MIL-53 nanozyme inducing ferroptosis and immunogenic cell death for cancer immunotherapy

Nanozymes offer diverse therapeutic potentials for cancer treatment which is dependent on the development of nanomaterials. Quasi-metal-organic framework is a class of metal-organic framework-derived nanomaterials with a transition state from metal-organic frameworks towards metal oxide featuring porous structure and high activity. Herein an iron-based quasi-metal-organic framework nanozyme Q-MIL-53(Fe) is reported via a controlled deligandation strategy, exhibiting enhanced peroxidase-/catalase-mimic activity and glutathione depletion capacity, whose underlying mechanisms are studied via density functional theory calculations. Q-MIL-53(Fe) demonstrates biocompatibility and superior antitumor efficacy compared to pristine MIL-53(Fe). It can activate antitumor immune response by inducing ferroptosis and immunogenic cell death, promoting dendritic cell maturation and T lymphocytes infiltration. Furthermore, a combination of Q-MIL-53(Fe) and programmed cell death protein 1 antibody amplifies cancer immunotherapy. This study validates the antitumor activity of quasi-metal-organic frameworks and its immunotherapy induction potential. It would broaden the application of quasi-metal-organic frameworks and open avenues for developing antitumor nanozymes.

A piezoelectric hydrogel containing bismuth sulfide with cationic vacancies with enhanced sonodynamic/nanozyme activity for synergistically killing bacteria and boosting osteoblast differentiation

A piezoelectric nanozyme is a novel biomaterial with the integration of piezoelectricity and nanozyme activity that has the capability of killing bacteria and promoting cell responses under a mechanical stimulus and exhibits great prospects in tissue regeneration. Herein, a piezoelectric nanozyme of bismuth sulfide (BS) with cationic vacancies (VBS) was synthesized, which exhibits enhanced piezoelectricity and nanozyme activities compared with BS. Moreover, a piezoelectric hydrogel of VBS and phenylboronic acid grafted sodium alginate-arginine (VBS-PSA) was prepared. Triggered by ultrasound (US) with high power (>0.5 W cm-2), VBS-PSA produces a large amount of reactive oxygen species (ROS) through both piezoelectricity-enhanced sonodynamic efficiency and peroxidase-like (POD-like) activity, thereby displaying the powerful antibacterial capability. However, under low-power US (≤0.5 W cm-2), the piezoelectric effect of VBS-PSA generates electrical signals that significantly stimulate the osteoblast responses (proliferation and osteoblast differentiation) and enhance catalase-like (CAT-like) activity for scavengers of ROS and generation of oxygen, thereby creating a favorable microenvironment for cell growth. Our study presents a novel strategy to apply the piezoelectric effect of hydrogels for enhancing sonodynamic efficiency and nanozyme activities that synergistically kill bacteria and stimulate osteoblast responses. The piezoelectric hydrogel would have great potential for the repair of infected bone defects.

Piezoelectric Biomaterial with Advanced Design for Tissue Infection Repair

Bacterial infection has become the most dangerous factor in tissue repair, which strongly affects the tissue regeneration efficiency and wellness of patients. Piezoelectric materials exhibit the outstanding advantage of producing electrons without external power supply. The ability of electron enrichment and reactive oxygen species generation through noninvasive stimulations enables piezoelectric materials the potential applications of antibacterial. Many studies have proved the feasibility of piezoelectric materials as a functional addition in antibacterial biomaterial. In fact, numerous piezoelectric materials with ingenious designs are reported to be effective in antibacterial processes. This review summarizes the antibacterial mechanisms of piezoelectric, illuminating their potential in combating bacteria. Recent advancement in the design and construction of piezoelectric biomaterial including defect engineering, heterojunction, synergy with metal and the composite scaffold configuration are thoroughly reviewed. Moreover, the applications and therapeutic effects of piezoelectric materials in common tissues with antibacterial requirements are introduced, such as orthopedics, dental, and wound healing. Finally, the development prospects and points deserving further exploration are listed. This review is expected to provide valuable insight into the relationship between antibacterial processes and piezoelectric materials, further inspiring constructive development in this emerging scientific discipline.

Pt(IV) prodrug as a potent nanosonosensitizer self-cyclically amplifies sonodynamic-chemotherapy with dually reversing cisplatin resistance

Although sonodynamic therapy (SDT) has shown promising advancements in combination with chemotherapy, it frequently necessitates the requirement of conventional sonosensitizers and chemotherapeutic agents, engendering intricate systems and potential drug resistance. Herein, we fabricated a potent Pt(IV)-poly(amino acid) coordination nanosonosensitizer (PHPt) with dual reversal of cisplatin resistance, producing abundant 1O2 and ˙OH upon ultrasound irradiation without the use of any external sonosensitizers. The Pt(IV) prodrug in PHPt efficiently reduced to cisplatin through SDT-induced ˙H and glutathione (GSH), inducing ˙OH accumulation and CDDP release, which further amplified the oxidative stress on SDT. Moreover, the high GSH depletion performance of PHPt and administration of aspirin effectively inhibited cisplatin detoxification and activation of the nuclear factor-kappa B pathway, respectively. This cooperative action between the Pt(IV) prodrug and SDT in the tumor microenvironment promoted self-cyclic amplification of sonodynamic-chemotherapy, achieving a significant tumor inhibition rate of 99.4%. Thus, this study offers novel perspectives on the sonosensitizer development and cisplatin application in SDT.

New horizons for the therapeutic application of nanozymes in cancer treatment

The advent of nanozymes has revolutionized approaches to cancer diagnosis and therapy, introducing innovative strategies that address the limitations of conventional treatments. Nanozyme nanostructures with enzyme-mimicking catalytic abilities exhibit exceptional stability, biocompatibility, and customizable functions, positioning them as promising tools for cancer theranostics. By emulating natural enzyme reactions, nanozymes can selectively target and eradicate cancer cells, minimizing harm to adjacent healthy tissues. Nanozymes can also be functionalized with specific targeting ligands, allowing for the precise delivery and regulated release of therapeutic agents, improving treatment effectiveness and reducing adverse effects. However, issues such as biocompatibility, selectivity, and regulatory compliance remain critical challenges for the clinical application of nanozymes. This review provides an overview of nanozymes, highlighting their unique properties, various classifications, catalytic activities, and diverse applications in cancer treatments. The strategic oncological deployment of nanozymes could profoundly impact future advancements in personalized medicine, highlighting recent progress and prospective directions in enzyme-mimetic approaches for cancer treatment. This review summarizes an overview of nanozymes, highlighting their unique properties, various classifications, catalytic activities, and diverse applications in cancer treatments.

Surface Bi-vacancy and corona polarization engineered nanosheets with sonopiezocatalytic antibacterial activity for wound healing

Piezocatalytic therapy is an emerging therapeutic strategy for eradicating drug-resistant bacteria, but suffers from insufficient piezoelectricity and catalytic active site availability. Herein, Bi-vacancies (BiV) and corona polarization were introduced to BiOBr nanosheets to create a BiOBr-BiVP nanoplatform for piezocatalytic antibacterial therapy. This meticulously tailored strategy strengthens the built-in electric field of nanosheets, enhancing piezoelectric potential and charge density and boosting charge separation and migration efficiency. Meanwhile, BiV adeptly adjust the band structure and increase reaction sites. Ultrasonication of nanosheets continuously enables the generation of reactive oxygen species (ROS) and CO, facilitating almost 100% broad-spectrum antibacterial efficacy. BiOBr-BiVP nanosheets demonstrate full bacterial eradication and accelerate wound healing through simultaneous regulation of inflammatory factors, facilitation of collagen deposition, and promotion of angiogenesis. Overall, this ultrasonic-triggered piezocatalytic nanoplatform combines BiV and the corona polarization strategy, providing a robust strategy for amplifying piezocatalytic mediated ROS/CO generation for drug-resistant bacterial eradication.

Neuroregulation during Bone Formation and Regeneration: Mechanisms and Strategies

The skeleton is highly innervated by numerous nerve fibers. These nerve fibers, in addition to transmitting information within the bone and mediating bone sensations, play a crucial role in regulating bone tissue formation and regeneration. Traditional bone tissue engineering (BTE) often fails to achieve satisfactory outcomes when dealing with large-scale bone defects, which is frequently related to the lack of effective reconstruction of the neurovascular network. In recent years, increasing research has revealed the critical role of nerves in bone metabolism. Nerve fibers regulate bone cells through neurotransmitters, neuropeptides, and peripheral glial cells. Furthermore, nerves also coordinate with the vascular and immune systems to jointly construct a microenvironment favorable for bone regeneration. As a signaling driver of bone formation, neuroregulation spans the entire process of bone physiological activities from the embryonic formation to postmaturity remodeling and repair. However, there is currently a lack of comprehensive summaries of these regulatory mechanisms. Therefore, this review sketches out the function of nerves during bone formation and regeneration. Then, we elaborate on the mechanisms of neurovascular coupling and neuromodulation of bone immunity. Finally, we discuss several novel strategies for neuro-bone tissue engineering (NBTE) based on neuroregulation of bone, focusing on the coordinated regeneration of nerve and bone tissue.

Piezoelectric-mediated two-dimensional copper-based metal-organic framework for synergistic sonodynamic and cuproptosis-driven tumor therapy

Sonodynamic therapy (SDT) is a minimally invasive therapeutic approach that utilizes sonosensitizers to catalyze substrates and generate reactive oxygen species (ROS) under ultrasound stimulation, ultimately inducing tumor cell death. Enhancing the piezoelectric properties of nanomaterials and modulating the semiconductor energy band are effective strategies to improve the catalytic efficiency of sonosensitizers. In this study, we developed a two-dimensional (2D) copper-based piezoelectric metal-organic framework (MOF) sonosensitizer, denoted as CM, through the coordination of copper and dimethylimidazole. The unique 2D MOF structure imparts CM with piezoelectric characteristics, enabling it to enhance SDT efficacy by modulating the semiconductor bandgap and carrier mobility. Upon ultrasound irradiation, CM catalyzes oxygen to undergo a cascade reaction, producing highly toxic singlet oxygen. Additionally, cupric ions in CM can be reduced by glutathione, facilitating the spontaneous catalysis of hydrogen peroxide in tumors to generate hydroxyl radicals and deplete glutathione, thereby inducing oxidative damage. Moreover, cupric ions in CM can trigger tumor cell cuproptosis, which, in combination with the generated ROS, accelerates cell death. Thus, this study establishes a MOF-based system for controllably inducing multi-pathway cancer cell death and provides a foundation for enhancing ultrasound-catalyzed tumor therapy through the optimization of piezoelectric properties.

Versatile Bi2MoO6/Prussian Blue-Au nanoplatform for oxygen-self-produced and GSH-depleted enhanced sonodynamic efficacy

Deprivation of oxygen and scavenging of reactive oxygen species (ROS) severely restrict the antitumor efficiency of sonodynamic therapy (SDT). To address these challs, we report the Bi2MoO6/Prussian Blue-Au (BMO/PB-Au) nanosystem as piezoelectric sonosensitiser for highly efficient ROS production under ultrasonic irradiation. In this system, the nanosystem has catalase-like (CAT) and glutathione oxidase (GSHOD) catalytic activity, which can enhance SDT effectively by producing reactive oxygen species and consuming glutathione (GSH). While the narrow bandgap and heterojunctions contribute to the improved charge separation and charge recombination suppression of the piezoelectric semiconductor BMO, accelerating ROS generation. Packaging MCF-7 cancer cell membranes (CM) on the surface of BMO/PB-Au will effectively improve the enrichment of nanoparticles in tumor tissue. The in vivo results showed that the BMO/PB-Au@CM nanoplatform can effectively inhibit tumor growth through the enhanced SDT effect. Our findings provide a paradigm to rationally design hypoxia-relieve and GSH-depleted SDT platform to for promoting cancer therapy efficiency.

Bismuth titanate microplates with tunable oxygen vacancies for piezocatalytic hydrogen peroxide production

Piezocatalysis offers an encouraging alternative for the sustainable, on-demand, and decentralized production of hydrogen peroxide (H2O2), underscoring the importance of enhancing piezocatalytic efficiency. Enhancing piezocatalysts through defect engineering has shown considerable potential in boosting H2O2 production efficiency. However, the impact of oxygen vacancies on piezocatalytic activity remains unclear. Herein, we used a chemical probe method to quantify negative charges (q-) and superoxide radicals (O2-) to explore the relation between the oxygen vacancy concentration and piezocatalytic performance of bismuth titanate (Bi4Ti3O12) based catalysts. Results indicate that piezocatalytic H2O2 production in pure water demonstrates a volcanic trend with increasing oxygen vacancy concentration. This trend is attributed to the dual role of oxygen vacancies, which reduce the piezoelectric property of the piezocatalyst while simultaneously increasing the concentration of O2-, which is crucial for H2O2 formation through the O2 reduction pathway. This study provides insights into the interplay between oxygen vacancies, piezoelectric properties, and piezocatalytic activity, offering valuable guidance for the design of piezocatalysts for sustainable H2O2 production.

Multi-Enzyme Mimetic MoCu Dual-Atom Nanozyme Triggering Oxidative Stress Cascade Amplification for High-Efficiency Synergistic Cancer Therapy

Single-atom nanozymes (SAzymes) with ultrahigh atom utilization efficiency have been extensively applied in reactive oxygen species (ROS)-mediated cancer therapy. However, the high energy barriers of reaction intermediates on single-atom sites and the overexpressed antioxidants in the tumor microenvironment restrict the amplification of tumor oxidative stress, resulting in unsatisfactory therapeutic efficacy. Herein, we report a multi-enzyme mimetic MoCu dual-atom nanozyme (MoCu DAzyme) with various catalytic active sites, which exhibits peroxidase, oxidase, glutathione (GSH) oxidase, and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase mimicking activities. Compared with Mo SAzyme, the introduction of Cu atoms, formation of dual-atom sites, and synergetic catalytic effects among various active sites enhance substrate adsorption and reduce the energy barrier, thereby endowing MoCu DAzyme with stronger catalytic activities. Benefiting from the above enzyme-like activities, MoCu DAzyme can not only generate multiple ROS, but also deplete GSH and block its regeneration to trigger the cascade amplification of oxidative stress. Additionally, the strong optical absorption in the near-infrared II bio-window endows MoCu DAzyme with remarkable photothermal conversion performance. Consequently, MoCu DAzyme achieves high-efficiency synergistic cancer treatment incorporating collaborative catalytic therapy and photothermal therapy. This work will advance the therapeutic applications of DAzymes and provide valuable insights for nanocatalytic cancer therapy.

Interface-Engineered CuxO@Bi2MoO6 Heterojunctions to Inhibit Piezoelectric Screening Effect and Promote Double-Nanozyme Catalysis for Antibacterial Treatment

Sonodynamic therapy is confronted with the low acoustic efficiency of sonosensitizers, and nanozymes are accompanied by intrinsic low catalytic activity. Herein, to increase the piezopotential of N-type piezoelectric semiconductors, the P-N heterojunction is designed to inhibit the piezoelectric screening effect (PSE) and increase electron utilization efficiency to enhance nanozyme activity. P-type CuxO nanoparticles are in situ grown on N-type piezoelectric Bi2MoO6 (BMO) nanoflakes (NFs) to construct heterostructured CuxO@BMO by interface engineering. CuxO deposition leads to lattice distortion of BMO NFs to improve piezoelectric response, and the strong interface electric field (IEF) suppresses PSE and increases piezopotential. The nonlocal piezopotential, local IEF, and glutathione (GSH) inoculation enhances electron-hole separation and increases peroxidase (POD)-like activity of BMO and GSH oxidase (GSHOx)-like activity of CuxO with high selectivity. The heterojunction formation causes the transfer and rearrangement of interface electrons, and the increased piezopotential accelerates electron transfer at interfaces with bacteria, thus increasing the production of reactive oxidative species and interfering with adenosine triphosphate synthesis. The heterostructured nanozymes produce abundant intracellular ·OH and achieve 4log magnitude reductions in viable bacteria and effective biofilm dispersion. This study elucidates integral mechanisms of nanozyme and acoustic catalysis and opens up a new way to synergize high piezopotential and nanozyme-catalyzed therapy.

Wearable Multifunctional Hydrogel for Oral Microenvironment Visualized Sensing Coupled with Sonodynamic Bacterial Elimination and Tooth Whitening

Bacterial-driven dental caries and tooth discoloration are growing concerns as the most common oral health problems. Current diagnostic methods and treatment strategies hardly allow simultaneous early detection and non-invasive treatment of these oral diseases. Herein, a wearable multifunctional double network hydrogel combined with polyaniline and barium titanate (PANI@BTO) nanoparticles is developed for oral microenvironment visualized sensing and sonodynamic therapy. Due to the colorimetric properties of polyaniline, the hydrogel displays a highly sensitive and selective response for visualized sensing of oral acidic microenvironment. Meanwhile, the barium titanate in the hydrogel efficiently generates reactive oxygen species (ROS) under ultrasound irradiation, realizing non-invasive treatment in the oral cavity. Through bacterial elimination experiments and tooth whitening studies, the hydrogel can achieve the dual effect of effectively inhibiting the growth of cariogenic bacteria and degrading tooth surface pigments. Owing to the visualized sensing of the oral acidic microenvironment and efficient sonodynamic therapy function, the proposed hydrogel system offers a solution for the prevention of caries and tooth whitening, which is promising in developing the biomedical system targeting the simultaneous sensing and therapy for oral diseases.

Charge Separation-Engineered Piezoelectric Ultrathin Nanorods Modulate Tumor Stromal Microenvironment and Enhance Cell Immunogenicity for Synergistically Piezo-Thermal-Immune Therapy

The tumor microenvironment (TME) is characterized by hypoxia and low immunogenicity, with a dense and rigid extracellular matrix (ECM) that impedes the diffusion of therapeutic agents and immune cells, thereby limiting the efficacy of immunotherapy. To overcome these challenges, an oxygen defect piezoelectric-photothermal sensitizer, bismuth vanadate nanorod-supported platinum nanodots (BVP) is developed. The integration of platinum enhances the photothermal effect and improves charge separation efficiency under ultrasound, leading to increased heat generation and the production of reactive oxygen species (ROS) and oxygen. Platinum also catalyzes the conversion of hydrogen peroxide in the TME to oxygen, which serves as both a ROS source and a means to alleviate tumor hypoxia, thereby reversing the immunosuppressive TME. Moreover, the coordination of bismuth ions with glutathione further amplifies cellular oxidative stress. The generated heat and ROS not only denature the collagen in the ECM, facilitating the deeper penetration of BVP into the tumor but also induce immunogenic cell death in tumor cells. Through the "degeneration and penetration" strategy, photoacoustic therapy effectively activates immune cells, inhibiting both tumor growth and metastasis. This study introduces a pioneering approach in the design of antitumor nanomedicines aimed at reversing the immunosuppressive characteristics of the TME.

Electronic band structure modulation for sonodynamic therapy

Sonodynamic therapy (SDT) is a burgeoning and newfangled therapy modality with great application potential. Sonosensitizers are essential factors used to ensure the effectiveness of SDT. For the past few years, a lot of scientists have discovered many valid ways to refine and improve the performance of SDT. Among these methods, modulating the electronic band structure of sonosensitizers is one of the eminent measures to improve SDT, but relevant research studies on this are still unsatisfactory for actual transformation. Herein, this review provides a brief and comprehensive introduction of common ways to modulate electronic band structure, such as forming defects, doping, piezoelectric effect and heterostructure. Then, some nanomaterials with excellent properties that can be used as a sonosensitizer to enhance the SDT effect by modulating electronic band structure are overviewed, such as Ti-based, Zn-based, Bi-based, noble metal-based and MOF-based nanomaterials. At the same time, this paper also discusses the problems and challenges that may be encountered in the future application progress of SDT. In conclusion, the strategy of enhancing SDT through modulating electronic band structure will promote the rapid development of nanomedicine and provide a great research direction for SDT.

Manganese Dioxide Coated Piezoelectric Nanosonosensitizer for Cancer Therapy with Tumor Microenvironment Remodeling and Multienzyme-Like Catalysis

Sonodynamic therapy (SDT) as an emerging method for cancer therapy has encountered difficulty in insufficient production of reactive oxygen species (ROS), especially in tumor microenvironment (TME) with elevated antioxidants and hypoxic conditions. In this work, the authors have fabricated heterostructured manganese dioxide (MnO2)-coated BaTiO3 nanoparticles (BTO@M NPs) as a piezoelectric sonosensitizer, which exhibits the capacity of remodeling TME and multienzyme-like catalysis for boosting SDT. Benefitting from the piezotronic effect, the formation of a p-n junction between MnO2 and piezoelectric BTO with a built-in electric field and band bending efficiently promotes the separation of charge carriers, facilitating the generation of superoxide anion (•O2 -) and hydroxyl radical (•OH) under ultrasound (US) stimulation. Moreover, BTO@M NPs can catalyze the overexpressed hydrogen peroxide (H2O2) in TME to produce oxygen for replenishing the gas source in SDT, and also deplete antioxidant glutathione (GSH), realizing TME remodeling. During this process, the reduced Mn(II) can convert H2O2 into •OH, further amplifying cellular oxidative damage. With these combination effects, the versatile BTO@M NPs exhibit prominent cytotoxicity and tumor growth inhibition against 4T1 breast cancer. This work provides a feasible strategy for constructing high-efficiency sonosensitizers for cancer SDT.

Engineering Strain-Defects to Enhance Enzymatic Therapy and Induce Ferroptosis

The effect of mimetic enzyme catalysis is often limited by insufficient activity and a single therapy is not sufficient to meet the application requirements. In this study, a multifunctional nanozyme, MMSR-pS-PEG, is designed and fabricated by modifying poly (ethylene glycol) grafted phosphorylated serine (pS-PEG) on mesoporous hollow MnMoOx spheres, followed by loading sorafenib (SRF) into the pores. Strain engineering-induced oxygen defects endow the nanozyme with enhanced dual-enzymatic activity to mimic catalase and oxidase-like activities, which catalyze the conversion of endogenous H2O2 into oxygen and subsequently into superoxide ions in the acidic tumor microenvironment. Moreover, as an n-type semiconductor, MnMoOx generates reactive oxygen species by separating electrons and holes upon ultrasonic irradiation and simultaneously deplete glutathione by holes, thereby further augmenting its catalytic effect. As a ferroptosis inducer, SRF restrains the system xc - and indirectly inhibits glutathione synthesis, synergistically interacting with the nanozyme to stimulate ferroptosis by promoting lipid peroxidation and accumulation and the downregulation of glutathione peroxidase 4. These results provide valuable insights into the design of enzymatic therapy with high performance and highlight a promising approach for the synergism of ferroptosis and enzymatic tumor therapy.

The advance of ultrasound-enabled diagnostics and therapeutics

Point-of-care ultrasound demonstrates significant potential in biomedical research due to its noninvasive, real-time visualization, cost-effectiveness, and other biological benefits. Ultrasound irradiation can precisely control the mechanical and physicochemical effects on pathogenic lesions, enabling real-time visualization, tunable tissue penetration depth, and therapeutic applications. This review summarizes recent advancements in ultrasound-enabled diagnostics and therapeutics, focusing on mechanochemical effects that can be directly integrated into biomedical applications. Additionally, the structure-functionality relationships of sonotheranostic nanoplatforms are systematically discussed, providing insights into the underlying biological effects. Finally, the limitations of current ultrasonic medicine are discussed, along with potential expansions to facilitate patient-centered translations.

Two-Dimensional Atomically Thin Piezoelectric Nanosheets for Efficient Pyroptosis-Dominated Sonopiezoelectric Cancer Therapy

Sonopiezocatalytic therapy is an emerging therapeutic strategy that utilizes ultrasound irradiation to activate piezoelectric materials, inducing polarization and energy band bending to facilitate the generation of reactive oxygen species (ROS). However, the efficient generation of ROS is hindered by the long distance of charge migration from the bulk to the material surface. Herein, atomically thin Bi2O2(OH)(NO3) (AT-BON) nanosheets are rationally engineered through disrupting the weaker hydrogen bonds within the [OH] and [NO3] layer in the bulk material. The ultrathin structure of AT-BON piezocatalytic nanosheets shortens the migration distance of carriers, expands the specific surface area, and accelerates the charge transfer efficiency, showcasing a natural advantage in ROS generation. Importantly, the non-centrosymmetric polar crystal structure grants the nanosheets the ability to separate electron-hole pairs. Under ultrasonic mechanical stress, Bi2O2(OH)(NO3) nanosheets with the remarkable piezoelectric feature exhibit the desirable in vivo antineoplastic outcomes in both breast cancer model and liver cancer model. Especially, the AT-BON-induced ROS bursts lead to the activation of the Caspase-1-driven pyroptosis pathway. This study highlights the beneficial impact of bulk material thinning on enhancing ROS generation efficiency and anti-cancer effects.

Engineering Sonosensitizer-Derived Nanotheranostics for Augmented Sonodynamic Therapy

Sonodynamic therapy (SDT), featuring noninvasive, deeper penetration, low cost, and repeatability, is a promising therapy approach for deep-seated tumors. However, the general or only utilization of SDT shows low efficiency and unsatisfactory treatment outcomes due to the complicated tumor microenvironment (TME) and SDT process. To circumvent the issues, three feasible approaches for enhancing SDT-based therapeutic effects, including sonosensitizer optimization, strategies for conquering hypoxia TME, and combinational therapy are summarized, with a particular focus on the combination therapy of SDT with other therapy modalities, including chemodynamic therapy, photodynamic therapy, photothermal therapy, chemotherapy, starvation therapy, gas therapy, and immunotherapy. In the end, the current challenges in SDT-based therapy on tumors are discussed and feasible approaches for enhanced therapeutic effects are provided. It is envisioned that this review will provide new insight into the strategic design of high-efficiency sonosensitizer-derived nanotheranostics, thereby augmenting SDT and accelerating the potential clinical transformation.

Nanosonosensitizer Optimization for Enhanced Sonodynamic Disease Treatment

Low-intensity ultrasound-mediated sonodynamic therapy (SDT), which, by design, integrates sonosensitizers and molecular oxygen to generate therapeutic substances (e.g., toxic hydroxyl radicals, superoxide anions, or singlet oxygen) at disease sites, has shown enormous potential for the effective treatment of a variety of diseases. Nanoscale sonosensitizers play a crucial role in the SDT process because their structural, compositional, physicochemical, and biological characteristics are key determinants of therapeutic efficacy. In particular, advances in materials science and nanotechnology have invigorated a series of optimization strategies for augmenting the therapeutic efficacy of nanosonosensitizers. This comprehensive review systematically summarizes, discusses, and highlights state-of-the-art studies on the current achievements of nanosonosensitizer optimization in enhanced sonodynamic disease treatment, with an emphasis on the general design principles of nanosonosensitizers and their optimization strategies, mainly including organic and inorganic nanosonosensitizers. Additionally, recent advancements in optimized nanosonosensitizers for therapeutic applications aimed at treating various diseases, such as cancer, bacterial infections, atherosclerosis, and autoimmune diseases, are clarified in detail. Furthermore, the biological effects of the improved nanosonosensitizers for versatile SDT applications are thoroughly discussed. The review concludes by highlighting the current challenges and future opportunities in this rapidly evolving research field to expedite its practical clinical translation and application.

Bifunctional Bismuth-Based Layered Double Hydroxide Sonosensitizer for Magnetic Resonance Imaging-Guided Sonodynamic Cancer Therapy

Novel inorganic sonosensitizers with excellent reactive oxygen species (ROS) generation activity and multifunctionality are appealing in sonodynamic therapy (SDT). Herein, amorphous bismuth (Bi)-doped CoFe-layered double hydroxide (a-CoBiFe-LDH) nanosheets are proposed via crystalline-to-amorphous phase transformation strategy as a new type of bifunctional sonosensitizer, which allows ultrasound (US) to trigger ROS generation for magnetic resonance imaging (MRI)-guided SDT. Importantly, a-CoBiFe-LDH nanosheets exhibit much higher ROS generation activity (≈6.9 times) than that of traditional TiO2 sonosensitizer under US irradiation, which can be attributed to the acid etching-induced narrow band gap, high electron (e-)/hole (h+) separation efficiency and inhibited e-/h+ recombination. In addition, the paramagnetic properties of Fe ion endow a-CoBiFe-LDH with excellent MRI contrast ability, making it a promising contrast agent for T2-weighted MRI. After modification with polyethylene glycol, a-CoBiFe-LDH nanosheets can function as a high-efficiency sonosensitizer to activate p53, MAPK, oxidative phosphorylation, and apoptosis-related signaling pathways, ultimately inducing cell apoptosis in vitro and tumor ablation in vivo under US irradiation, which shows great potential for clinical cancer treatment.

Zn/Pt dual-site single-atom driven difunctional superimposition-augmented sonosensitizer for sonodynamic therapy boosted ferroptosis of cancer

Sonodynamic therapy (SDT) as a non-invasive antitumor strategy has been widely concerned. However, the rapid electron (e-) and hole (h+) recombination of traditional inorganic semiconductor sonosensitizers under ultrasonic (US) stimulation greatly limits the production of reactive oxygen species (ROS). Herein, we report a unique Zn/Pt dual-site single-atom driven difunctional superimposition-augmented TiO2-based sonosensitizer (Zn/Pt SATs). Initially, we verify through theoretical calculation that the strongly coupled Zn and Pt atoms can assist electron excitation at the atomic level by increasing electron conductivity and excitation efficiency under US, respectively, thus effectively improving the yield of ROS. Additionally, Zn/Pt SATs can significantly enhance ferroptosis by producing more ROS and sonoexcited holes under US stimuli. Therefore, the establishment of dual-site single-atom system represents an innovative strategy to enhance SDT in cancer model of female mice and provides a typical example for the development of inorganic sonosensitizer in the field of antitumor therapy.

Doping-Engineered Piezoelectric Ultrathin Nanosheets for Synergistically Piezo-Chemocatalytic Antitumor and Antibacterial Therapies Against Cutaneous Melanoma

The post-surgical melanoma recurrence and wound infections have persistently troubled clinical management. Piezocatalytic therapy features high efficiency in generating reactive oxygen species (ROS) for tumor therapy, but it faces limitations in piezoelectricity and redox-active site availability. Herein, Fe-doped ultrathin Bi4Ti3O12 nanosheets (designated as Fe-UBTO NSs) with synergistically piezo-chemocatalytic activity are engineered for antitumor and antibacterial treatment against cutaneous melanoma. The doping-engineered strategy induces oxygen vacancies and lattice distortions in Fe-UBTO NSs, which narrows bandgap to enhance piezocatalytic 1O2 and H2O2 generation by improving the electron-hole pairs separation, hindering their recombination, and increasing oxygen adsorption. Moreover, Fe doping establishes a piezo-chemocatalytic system, in which the piezocatalysis enables the self-supply of H2O2 and expedites electron transfer in Fenton reactions, inducing increased ·OH production. Besides, the atomic-level thickness and expanded surface area enhance the sensitivity to ultrasound stimuli and expose more redox-active sites, augmenting the piezo-chemocatalytic efficiency, and ultimately leading to abundant ROS generation. The Fe-UBTO-mediated piezo-chemocatalytic therapy causes intracellular oxidative stress, triggering apoptosis and excessive autophagy of tumor cells. Moreover, this strategy accelerates wound healing by facilitating sterilization, angiogenesis, and collagen deposition. This work provides distinct options to develop doping-engineered ultrathin nanosheets with augmented piezo-chemocatalytic activity for postoperative management of cutaneous melanoma.

Piezoelectric Bilayer Nickel-Iron Layered Double Hydroxide Nanosheets with Tumor Microenvironment Responsiveness for Intensive Piezocatalytic Therapy

Piezocatalytic therapy (PCT) based on 2D layered materials has emerged as a promising non-invasive tumor treatment modality, offering superior advantages. However, a systematic investigation of PCT, particularly the mechanisms underlying the reactive oxygen species (ROS) generation by 2D nanomaterials, is still in its infancy. Here, for the first time, biodegradable piezoelectric 2D bilayer nickel-iron layered double hydroxide (NiFe-LDH) nanosheets (thickness of ≈1.86 nm) are reported for enhanced PCT and ferroptosis. Under ultrasound irradiation, the piezoelectric semiconducting NiFe-LDH exhibits a remarkable ability to generate superoxide anion radicals, due to the formation of a built-in electric field that facilitates the separation of electrons and holes. Notably, the significant excitonic effect in the ultrathin NiFe-LDH system enables long-lived excited triplet excitons (lifetime of ≈5.04 µs) to effectively convert triplet O2 molecules into singlet oxygen. Moreover, NiFe-LDH exhibited tumor microenvironment (TME)-responsive peroxidase (POD)-like and glutathione (GSH)-depleting capabilities, further enhancing oxidative stress in tumor cells and inducing ferroptosis. To the best of knowledge, this is the first report on piezoelectric semiconducting sonosensitizers based on LDHs for PCT and ferroptosis, providing a comprehensive understanding of the piezocatalysis mechanism and valuable references for the application of LDHs and other 2D materials in cancer therapy.

A GSH-Responsive Prodrug with Simultaneous Triple-Activation Capacity for Photodynamic/Sonodynamic Combination Therapy with Inhibited Skin Phototoxicity

Herein, a dual-sensitizer prodrug, named pro-THPC, has been designed to function as both a photosensitizer and a sonosensitizer prodrug for precise antitumor combination therapy with minimized skin phototoxicity. Pro-THPC could be activated by glutathione (GSH) to release the dual-sensitizer, THPC, which simultaneously switches on fluorescence emission and combined capabilities of photodynamic therapy (PDT) and sonodynamic therapy (SDT). Pro-THPC is further formulated into nanoparticles (NPs) for water dispersity to enable in vivo applications. In vivo fluorescence imaging shows that the pro-THPC NPs group exhibits a significantly higher tumor-to-normal tissue ratio (T/N) (T/N = 5.2 ± 0.55) compared to the "always on" THPC NPs group (T/N = 2.9 ± 0.47) and the pro-THPC NPs group co-administrated with GSH synthesis inhibitor (buthionine sulfoximine, BSO) (T/N = 3.2 ± 0.63). In addition, the generation of the designed dual-sensitizer's reactive oxygen species (ROS) is effectively confined within the tumor tissues due to the relatively strong correlation between ROS generation and fluorescence emission. In vivo studies further demonstrate the remarkable efficacy of the designed pro-THPC NPs to eradicate tumors through the combination of PDT and SDT while significantly reducing skin phototoxicity.

What Is the Magical Cavitation Bubble: A Holistic Perspective to Trigger Advanced Bubbles, Nano-Sonocatalysts, and Cellular Sonosensitizers

Sonodynamic therapy (SDT) has emerged as a novel and highly researched advancement in the medical field. Traditional ultrasound contrast agents and novel bubble-shaped agents are used to stimulate cavitation and enhance SDT efficiency. However, the impact of artificially modified shell structures on the acoustic properties of microbubbles remains to be explored. Alternatively, in the absence of bubble-shaped agents, some clinically available organic sonosensitizers and advanced inorganic materials are also used to enhance the efficacy of SDT. Diagnostic and therapeutic ultrasound can also activate cavitation bubbles, which supply energy to sonosensitive agents, leading to the production of cytotoxic free radicals to achieve therapeutic effects. While inorganic materials often spark controversy in clinical applications, their relatively simple structure enables researchers to gain insight into the mechanism by which SDT produces various free radicals. Some organic-inorganic hybrid sonosensitive systems have also been reported, combining the benefits of inorganic and organic sonosensitive agents. Alternatively, by employing cell surface modification engineering to enable cells to perform functions such as immune escape, drug loading, gas loading, and sonosensitivity, cellular sonosensitizers have also been developed. However, further exploration is needed on the acoustic properties, ability to generate reactive oxygen species (ROS), and potential clinical application of this cellular sonosensitizer. This review offers a comprehensive analysis of vesical microbubbles and nanoscale sonocatalysts, including organic, inorganic, combined organic-inorganic sonosensitizers, and cellular sonosensitizers. This analysis will enhance our understanding of SDT and demonstrate its important potential in transforming medical applications.

Ba2+-doping introduced piezoelectricity and efficient Ultrasound-Triggered bactericidal activity of brookite TiO2 nanorods

Exploring highly efficient ultrasound-triggered catalysts is pivotal for various areas. Herein, we presented that Ba2+ doped brookite TiO2 nanorod (TiO2: Ba) with polarization-induced charge separation is a candidate. The replacement of Ba2+ for Ti4+ not only induced significant lattice distortion to induce polarization but also created oxygen vacancy defects for facilitating the charge separation, leading to high-efficiency reactive oxygen species (ROS) evolution in the piezo-catalytic processes. Furthermore, the piezocatalytic ability to degrade dye wastewater demonstrates a rate constant of 0.172 min-1 and achieves a 100 % antibacterial rate at a low dose for eliminating E. coli. This study advances that doping can induce piezoelectricity and reveals that lattice distortion-induced polarization and vacancy defects engineering can improve ROS production, which might impact applications such as water disinfection and sonodynamic therapy.

A Functional "Key" Amplified Piezoelectric Effect Modulates ROS Storm with an Open Source for Multimodal Synergistic Cancer Therapy

Chemodynamic therapy (CDT) is a non-invasive strategy for generating reactive oxygen species (ROS) and is promising for cancer treatment. However, increasing ROS in tumor therapy remains challenging. Therefore, exogenous excitation and inhibition of electron-hole pair recombination are attractive for modulating ROS storms in tumors. Herein, a Ce-doped BiFeO3 (CBFO) piezoelectric sonosensitizer to modulate ROS generation and realize a synergistic mechanism of CDT/sonodynamic therapy and piezodynamic therapy (PzDT) is proposed. The mixed Fe2+ and Ce3+ can implement a circular Fenton/Fenton-like reaction in the tumor microenvironment. Abundant ·OH can be generated by ultrasound (US) stimulation to enhance CDT efficacy. As a typical piezoelectric sonosensitizer, CBFO can produce O2 - owing to the enhanced polarization by the US, resulting in the motion of charge carriers. In addition, CBFO can produce a piezoresponse irradiated upon US, which accelerates the migration rate of electrons/holes in opposite directions and results in energy band bending, further achieving toxic ROS production and realizing PzDT. Density functional theory calculations confirmed that Ce doping shortens the diffusion of electrons and improves the conductivity and catalytic activity of CBFO. This distinct US-enhanced strategy emphasizes the effects of doping engineering and piezoelectric-optimized therapy and shows great potential for the treatment of malignant tumors.

Revealing the Optimization Route of Piezoelectric Sonosensitizers: From Mechanism to Engineering Methods

Piezoelectric catalysis is a novel catalytic technology that has developed rapidly in recent years and has attracted extensive interest among researchers in the field of tumor therapy for its acoustic-sensitizing properties. Nevertheless, researchers are still controversial about the key technical difficulties in the modulation of piezoelectric sonosensitizers for tumor therapy applications, which is undoubtedly a major obstacle to the performance modulation of piezoelectric sonosensitizers. Clarification of this challenge will be beneficial to the design and optimization of piezoelectric sonosensitizers in the future. Here, the authors start from the mechanism of piezoelectric catalysis and elaborate the mechanism and methods of defect engineering and phase engineering for the performance modulation of piezoelectric sonosensitizers based on the energy band theory. The combined therapeutic strategy of piezoelectric sonosensitizers with enzyme catalysis and immunotherapy is introduced. Finally, the challenges and prospects of piezoelectric sonosensitizers are highlighted. Hopefully, the explorations can guide researchers toward the optimization of piezoelectric sonosensitizers and can be applied in their own research.

Peptide-Functionalized Inorganic Oxide Nanomaterials for Solid Cancer Imaging and Therapy

The diagnosis and treatment of solid tumors have undergone significant advancements marked by a trend toward increased specificity and integration of imaging and therapeutic functions. The multifaceted nature of inorganic oxide nanomaterials (IONs), which boast optical, magnetic, ultrasonic, and biochemical modulatory properties, makes them ideal building blocks for developing multifunctional nanoplatforms. A promising class of materials that have emerged in this context are peptide-functionalized inorganic oxide nanomaterials (PFIONs), which have demonstrated excellent performance in multifunctional imaging and therapy, making them potential candidates for advancing solid tumor diagnosis and treatment. Owing to the functionalities of peptides in tumor targeting, penetration, responsiveness, and therapy, well-designed PFIONs can specifically accumulate and release therapeutic or imaging agents at the solid tumor sites, enabling precise imaging and effective treatment. This review provides an overview of the recent advances in the use of PFIONs for the imaging and treatment of solid tumors, highlighting the superiority of imaging and therapeutic integration as well as synergistic treatment. Moreover, the review discusses the challenges and prospects of PFIONs in depth, aiming to promote the intersection of the interdisciplinary to facilitate their clinical translation and the development of personalized diagnostic and therapeutic systems by optimizing the material systems.

Surface-Integrating Oxygen Vacancy and CuxO Nanodots Enabling Synergistic Electric Field and Dual Catalytic Sites Boosting CO2 Photoreduction

High carrier separation efficiency and rapid surface catalytic reaction are crucial for enhancing catalytic CO2 photoreduction reaction. Herein, integrated surface decoration strategy with oxygen vacancies (Ov) and anchoring CuxO (1 < x < 2) nanodots below 10 nm is realized on Bi2MoO6 for promoting CO2 photoreduction performance. The charge interaction between Ov and anchored CuxO enables the formation of enhanced internal electric field, which provides a strong driving force for accelerating the separation of photocharge carriers on the surface of Bi2MoO6 (ηsurf ≈71%). They can also cooperatively reduce the surface work function of Bi2MoO6, facilitating the migration of carrier to the surface. Meanwhile, surface-integrated Ov and CuxO nanodots allowing dual catalytic sites strengthens the adsorption and activation CO2 into *CO2 over Bi2MoO6, considerably boosting the progression of CO2 conversion process. In the absence of co-catalyst or sacrificial agent, Bi2MoO6 with Ov and CuxO nanodots achieves a photocatalytic CO generation rate of 12.75 µmol g-1 h-1, a remarkable increase of over ≈15 times that of the original counterpart. This work provides a new idea for governing charge movement behaviors and catalytic reaction thermodynamics on the basis of synergistic improvement of electric field and active sites by coupling of the internal defects and external species.

Four Birds with One Stone: A Bandgap-Regulated Multifunctional Schottky Heterojunction for Robust Synergistic Antitumor Therapy upon Endo-/Exogenous Stimuli

Considering the profound impact of structure on heterojunction catalysts, the rational design of emerging catalysts with optimized energy band structures is required for antitumor efficiency. Herein, we select titanium nitride (TiN) and Pt to develop a multifunctional Schottky heterojunction named Pt/H-TiN&SRF (PHTS) nanoparticles (NPs) with a narrowed bandgap to accomplish "four birds with one stone" involving enzyo/sono/photo three modals and additional ferroptosis. The in situ-grown Pt NPs acted as electron traps that can cause the energy band to bend upward and form a Schottky barrier, thereby facilitating the separation of electron/hole pairs in exogenous stimulation catalytic therapy. In addition, endogenous catalytic reactions based on peroxidase (POD)- and catalase (CAT)-mimicking activities can also be amplified, triggering intense oxidative stress, in which CAT-like activity decomposes endogenous H2O2 into O2 alleviating hypoxia and provides reactants for sonodynamic therapy. Moreover, PHTS NPs can elicit mild photothermal therapy with boosted photothermal properties as well as ferroptosis with loaded ferroptosis inducer sorafenib for effective tumor ablation and apoptosis-ferroptosis synergistic tumor inhibitory effect. In summary, this paper proposes an attractive design for antitumor strategies and highlights findings for heterojunction catalytic therapy with potential in tumor theranostics.

Ternary Bi2WO6/TiO2-Pt Heterojunction Sonosensitizers for Boosting Sonodynamic Therapy

Engineering Z-scheme heterojunctions represents a promising strategy for optimizing the separation and migration of charge carriers in semiconductor sonosensitizers for enhanced reactive oxygen species (ROS) generation. Nevertheless, establishing a continuous and directional pathway for ultrasonic-induced charge flow in Z-scheme heterojunctions remains a significant challenge. In this study, we present a ternary Bi2WO6/TiO2-Pt heterojunction sonosensitizer achieved through the precise growth of Pt nanocrystals on a directionally assembled Bi2WO6/TiO2 Z-scheme structure. The construction of the Bi2WO6/TiO2-Pt heterojunction involves directional growth of Bi2WO6 in situ on the highly exposed (001) crystal facet of TiO2 nanosheets, followed by the precise deposition of nano Pt on the edge (101) crystal facet. The Z-scheme Bi2WO6/TiO2 in the ternary heterojunction ensures effective electron separation, while the Schottky TiO2-Pt interface establishes a well-defined charge flow path and robust redox capabilities. Moreover, nano Pt confers the Bi2WO6/TiO2-Pt heterojunction with excellent peroxidase-mimic and catalase-mimic activities, facilitating interactions with endogenous H2O2 to produce the hydroxyl radicals and O2. It effectively alleviates tumor hypoxia and enhances ROS production. This results in significantly higher efficiency in sonodynamically induced ROS generation compared to pure TiO2 or binary Bi2WO6/TiO2 heterojunctions, as confirmed by DFT theoretical calculation and experiments with both in vitro and in vivo anticancer performance. This study offers valuable insights for designing high-performance Z-scheme sonosensitizer systems.

Surface Oxygen Vacancies and Corona Polarization of Bi4Ti3O12 Nanosheets for Synergistically Enhanced Sonopiezoelectric Therapy

Sonopiezoelectric therapy, an ultrasound-activated piezoelectric nanomaterial for tumor treatment, has emerged as a novel alternative modality. However, the limited piezoelectric catalytic efficiency is a serious bottleneck for its practical application. Excellent piezoelectric catalysts with high piezoelectric coefficients, good deformability, large mechanical impact surface area, and abundant catalytically active sites still need to be developed urgently. In this study, the classical ferroelectric material, bismuth titanate (Bi4Ti3O12, BTO), is selected as a sonopiezoelectric sensitizer for tumor therapy. BTO generates electron-hole pairs under ultrasonic irradiation, which can react with the substrates in a sonocatalytic-driven redox reaction. Aiming to further improve the catalytic activity of BTO, modification of surface oxygen vacancies and treatment of corona polarization are envisioned in this study. Notably, modification of the surface oxygen vacancies reduces its bandgap and inhibits electron-hole recombination. Additionally, the corona polarization treatment immobilized the built-in electric field on BTO, further promoting the separation of electrons and holes. Consequently, these modifications greatly improve the sonocatalytic efficiency for in situ generation of cytotoxic ROS and CO, effectively eradicating the tumor.

Sulfur-Vacancy-Engineered Two-Dimensional Cu@SnS2-x Nanosheets Constructed via Heterovalent Substitution for High-Efficiency Piezocatalytic Tumor Therapy

Ultrasound (US)-mediated piezocatalytic tumor therapy has attracted much attention due to its notable tissue-penetration capabilities, noninvasiveness, and low oxygen dependency. Nevertheless, the efficiency of piezocatalytic therapy is limited due to an inadequate piezoelectric response, low separation of electron-hole (e--h+) pairs, and complex tumor microenvironment (TME). Herein, an ultrathin two-dimensional (2D) sulfur-vacancy-engineered (Sv-engineered) Cu@SnS2-x nanosheet (NS) with an enhanced piezoelectric effect was constructed via the heterovalent substitution strategy of Sn4+ by Cu2+. The introduction of Cu2+ ion not only causes changes in the crystal structure to increase polarization but also generates rich Sv to decrease band gap from 2.16 to 1.62 eV and inhibit e--h+ pairs recombination, collectively leading to the highly efficient generation of reactive oxygen species under US irradiation. Moreover, Cu@SnS2-x shows US-enhanced TME-responsive Fenton-like catalytic activity and glutathione depletion ability, further aggravating the oxidative stress. Both in vitro and in vivo results prove that the Sv-engineered Cu@SnS2-x NSs can significantly kill tumor cells and achieve high-efficiency piezocatalytic tumor therapy in a biocompatible manner. Overall, this study provides a new avenue for sonocatalytic therapy and broadens the application of 2D piezoelectric materials.